Other Mod Hosting sites:
UI.WorldofWar
Curse-Gaming
The
sticky thread at the top of the
Official Blizz UI & Macros forum, of course.
Plus all the authors that self-host, most of which can be found by browsing through the
Official Blizz UI & Macros forum.
Macro/Scripting Sites:
You can find a lot in another
sticky thread at the top of the
Official Blizz UI & Macros forum.
As well as at these sites:
WoWWiki
WoWMacros